HTTP 406 Not Acceptable

In short: The server cannot deliver a response in any of the formats the client accepts.

In more detail: The client names in Accept, Accept-Language or Accept-Encoding what it can understand. If the server finds nothing suitable it answers 406 (many servers simply deliver their default format instead).

In Depth

When it occurs

• API call with Accept: application/xml while the server only knows JSON.
• Very strict server configuration with modules such as mod_security.

What you can do

1. Relax or omit the Accept header.
2. Operators: offer a default format instead of rejecting hard; check rules of security modules.

See also: HTTP Status Codes Overview, HTTP